CORN Watch for Japanese Beetle on “Silking” Corn By Doug Johnson Japanese beetles have been emerging over the last couple of weeks. With the general rainfall we had last Monday (6/11/12) this emergence is likely to quicken. While this insect will feed on corn leaves, its’ only real importance is when feeding on emerging silks. This silk feeding can interfere with pollination resulting in incomplete kernel set.

These insects are metallic green beetles about ½ “ long. They have a row of white tufts on either side of the body below the bronze wing covers. The beetles will congregate (sometimes in very large numbers) on ear tips and feed on the silks, thus preventing proper pollination. Normally, this insect is not a major pest of corn. However, in this year because of the mild winter and very warm spring the pest is emerging at an earlier date. Also, because of the dry soil conditions in the western part of the state, the emergence which is normally spread out in time, may occur over a much shorter time period producing an unusually large number of beetles seemingly all at once. Scout for this insect by examining several individual groups of 20 consecutive ears. Determine if the silks have been clipped to within 1/2” in length. Additionally, count the number of beetles per ear and average these numbers for the twenty ears per sample, then average all the samples taken in the field. Treatment may be necessary if silks have been clipped to ½” and there are three or more beetles per ear.

There are several important wild bee pollinators of cucurbits, and to some extent the cast of pollinators depends on the type of cucurbit species. Basically there are two types of cucurbit flowers; the small melon, watermelon and cucumber flowers, and the larger squash and pumpkin flowers. Logan Miner, PhD student in Entomology, has been conducting surveys of pollinators in squash and melon fields the past three years. Here’s what he has found through surveying commercial farms. Bumble bees: Several species are very common to both melons and squashes in Kentucky, but Bombus impatiens appears to be the most common. Bumble bees are common early in the day often before honey bees are foraging. Bumble bees are considered very effective pollinators of cucurbirts.

CUCURBITS Pollination of Cucurbits By Ric Bessin There has been considerable concern over the loss in numbers of honey bees over the past 6 years and some cucurbit growers have expressed concern over the lack of pollinators. Cucurbits are entirely dependent on insect pollinations, it is simple: No insect pollinators, no fruit. Honey bees are fantastic as pollinators of these crops as they are so easily manipulated by moving in colonies as needed. In the absence of pollinator activity, honey bee colonies can be moved in quickly to provide necessary pollination services typically at the rate of one or two colonies per acre. With vegetable farms in Kentucky, many growers have been able to rely on wild honey bees moving from surrounding areas to pollinate smaller acreages, but concern has been increasing with the recent losses.

Figure 3. Bombus impatiens is a common pollinator of both squash and melon flowers.

Squash bee: The squash bee is a specialist for squash flowers and pollinates little else (sometimes found pollinating morning glory). Squash bees do not pollinate melon flowers. Squash bees are very common and build individual nests in bare or nearly bear ground. The squash bee looks similar to honey bees, but is a bit larger , ‘hairier’, with more colored banding

of the abdomen. Squash bees are often the first pollinators to begin in the morning often working flowers before sunrise. Early in the summer, males and female squash bees can be found sleeping in wilted squash flowers from early afternoon until the next morning.

Generally, when female flowers begin to open, those are the flowers that have a tiny fruit just below the flower, growers should monitor for adequate pollination activity. On a warm sunny day with little wind, pollinators should be common in the planting by mid-morning. If pollinators are lacking, growers may need to contact a local beekeeper to move bees near the field. Misshapen or fruit failing to size are often indicators of poor pollination.

VEGETABLES Bacterial Fruit Blotch Found on Watermelon By Kenny Seebold Bacterial fruit blotch was confirmed recently greenhouse-grown transplants of seedless watermelon (‘Utopia’), and also ‘Athena’ cantaloupe. We also found active disease on plants in the field that had come from the greenhouses in question. The first-ever case of this disease in Kentucky was reported last year and caused a significant amount of damage to one grower’s field. The pathogen, Acidovorax avenae subsp. citrulli, is a bacterium that is spread mainly on seed. The disease can affect most cucurbits; however, watermelon tends to be most susceptible. Symptoms of bacterial fruit blotch often appear first on seedlings in greenhouses as water-soaked areas on the undersides of cotyledons (Fig. 5). These lesions eventually turn necrotic and take on a reddish-brown color, extending along the midrib of affected cotyledons (Fig. 6). The pathogen is easily spread in greenhouse environments by physical contact or water splash, and symptoms can develop on true leaves. When infected plants are set in the field, secondary infections can occur during warm, rainy periods. Symptoms appear as necrotic, angular areas (Fig. 7); foliar symptoms in the field may be difficult to see, particularly as canopy density increases. During fruit set, bacteria can be spread from foliar lesions (or infected melons) to developing fruit following

Figure 4. The squash bee in often the earliest first to begin pollinating in the morning.

Long-horned bees (Melissodes bimaculata): This Melissodes species is about the same size as a honey bee, almost black in color with a pair of light colored marking on the abdomen and light colored hairs on the hind legs. These groundnesting bees fly very quickly between flowers and do not spend much time in any one flower. Logan Minter has observed them going under the plastic mulch to nest and can be common in squash fields. Sweat bees (Agapostemon spp. And Lasioglossum spp.): Smallish black and metallic green bees. There are many species and distinguishing them can be impractical. As a group these may be the most common group of pollinators, but there contribution to adequate on a per visit basis may be considerably less than that the pollinators listed above. While they may lack the efficiency of the larger pollinators, they can be frequent flower visitors.

rain, irrigation, or mechanical contact. Fruit are most susceptible to infection during the first 2-3 weeks of development; after this period, a waxy layer is present on the rinds of fruit that significantly reduces the ability of the pathogen to infect. Symptoms on fruit appear first as watersoaked, darkened areas on the upper portions of melons (Fig. 8). These areas expand, and the rind can eventually crack. Liquid or foam can be expelled from cracked areas during hot weather (Fig. 9). For the moment, we have observed bacterial fruit blotch mainly on ‘Utopia’ watermelons, and growers with this variety should scout greenhouses and fields for symptoms of this disease. Control of bacterial fruit blotch can be difficult under disease-favorable conditions (warm and wet weather). If the disease is found in the greenhouse, all seedlings should be destroyed to prevent introduction of the pathogen into the field. If infected seedlings are set in the field, or if the disease is observed on newly-set plants, weekly applications of copper fungicide are recommended. Sprays should continue until 3-4 weeks after fruit set. Rotate away from fields affected by fruit blotch for 2-3 years and destroy volunteer melons that may emerge.

Both cultural practices and fungicides are critical for control of black rot. Fruit mummies must be removed from vineyards to eliminate sources of overwintering inoculum. Beginning at pre-bloom, a rigid fungicide regime must be employed. Strobilurin fungicides (Abound, Pristine, Flint) provide excellent control, but risk for fungicide resistance is high. Rotate with triazole/SI fungicides (Bayleton, Elite, Rally) and protectant fungicides (Mancozeb, Ziram). Commercial growers should refer to the Midwest Small Fruit and Grape spray guide for fungicide and schedule details, while homeowners can use fungicides listed in ID-21 and PPFS-misc-7. These and other publications can be found at http://www.ca.uky.edu/agcollege/plantpathology/e xtension/pubs.html#Smallfruit

Figure 9. Cracking and ooze associated with bacterial fruit blotch.

FRUIT CROPS Black Rot of Grape By Nicole Ward Black rot is the most common disease of grape in Kentucky. If left unprotected, vineyards can suffer high economic losses. Infection occurs early in the season, usually before bloom, at temperatures as low as 50˚F. Early symptoms develop as spots on leaves 1 to 2 weeks after infection (Fig 10). Tan spots with darker margins often contain black fruiting structures (pycnidia) in centers (Fig.11). Spores (conidia) from these structures cause secondary infections throughout the season. As leaves mature, they become resistant, but newly developing leaves can become infected anytime during the season. Fruit infections occur early in the spring, as well. Grapes are susceptible from flowering until 3 to 4 weeks after bloom. Early fruit symptoms appear as light brown spots (Fig. 12). Soon, entire berries turn dark brown and shrivel (Fig 13). These raisin-like fruit develop black fruiting structures (pycnidia) that overwinter on the “mummies.”
Figure 10. Leaf lesions have light tan centers and darker brown margins.

Figure 11. Fruiting structures (Pycnidia) produce spores that cause secondary infections. They can be seen with a magnifying glass, and often with the naked eye.

ORNAMENTALS & SHADE TREES Impatiens Downy Mildew By Nicole Ward Downy mildew of impatiens caused quite a stir in the region last year. Luckily, we did not see this devastating disease in Kentucky. Last week, the pathogen was identified in multiple landscapes in North Carolina, so our risk for detection here in Kentucky is high.
Figure 12. Fruit infections begin as light brown spots. Note: bird's eye rot (anthracnose) infections on fruit have dark reddish margins with light gray centers.

Downy mildew of impatiens is caused by the ‘water mold’ Plasmopara obducens. Like other downy mildew pathogens, this organism favors cool, wet/humid conditions. Although it has been quite dry in the region, impatiens downy mildew can originate in propagation greenhouses, and then thrive in irrigated landscapes and retail nurseries. Once established, the pathogen is spread by wind currents, water splash, and by movement of infected plants. Most types of impatiens (Impatiens walleriana, including double impatiens and mini-impatiens, and any I. walleriana interspecific hybrids, such as Fusion® impatiens) are susceptible to downy mildew. However, New Guinea impatiens (I. hawkeri) and interspecific hybrids such as SunPatiens® are tolerant to the disease. Fungicides are not recommended for management of impatiens downy mildew, as inconsistencies have been reported. Remove all infected plants, and destroy by burying or burning. Contact N. Ward or the UK Plant Disease Diagnostic Laboratory if you suspect impatiens downy mildew in your nursery or landscape.

Figure 13. Soon after infection, grapes with black rot disease turn dark and shrivel into hard, black mummies. Fruiting bodies (pycnidia) that develop are the primary source of overwintering for this fungus.

Figure 14. Infected leaves may include classic downy mildew symptoms - white-colored fungal growth and sporulation. If conditions are hot or dry, sporulation may not be visible (K. Ivors).

but healthy established trees are rarely harmed. These aphids produce sugar-rich liquid waste (honeydew) that drips onto foliage and branches below them attracting bees, wasps, and flies. Sooty mold fungus can grow on the honeydew deposits, blackening leaves and branches and making objects below sticky. Wooly alder aphids can be a nuisance but usually do not damage healthy, established silver maples. Also, they leave them for alder by about mid-June so control is not needed. After arriving on alder, the aphids will settle and feed during the summer months, also producing wool. Some will remain on alder during the winter. A few male and female aphids will return to maple and mate. Each female will lay a single egg in a bark crack or crevice which will remain there over the winter. The eggs will hatch in the spring and repeat the life cycle.

Woolly Aphids By Lee Townsend Woolly aphids are group of sap-feeding insects that produce white filaments resembling strands of cotton or wool. The woolly alder aphid has been especially abundant this year and may become more so as wool-streaming adults drift through the air in hopes of finding their alternative hosts. You may have seen this one or other species this spring. LIVESTOCK Darkling/Mealworm Beetles in Hay or Feed By Lee Townsend Finding beetles in stored alfalfa hay or animal feed raises an immediate red flag. Are they blister beetles? If not, what are they and are they harmful? Usually, it is darkling beetles, they larvae are called mealworms. These insects tend to hide so they can be found under, in, or between stacked hay bales. Darkling beetles do not contain cantharidin, the toxin in blister beetles, they are not harmful. Darkling beetles are different from blister beetles. The most obvious feature is the distinctly narrow “neck” of a blister beetle which lies between the head and thorax of the insect. In contrast, the “neck” area of the darkling beetle is wider than its head. Also, they have hard front wings compared to the soft, more flexible front wings of blister beetles.

Figure 16. Waxy filaments of woolly aphids.

Woolly alder aphids are sap feeders that split their life cycle between silver maple and alder. Thin strands of white woolly wax develop as the aphids feed and grow. Infested leaves may curl or pucker

Mealworms, the larval stage of the darkling beetle, are common in stored or spilled grain or feed, where they eat broken kernels and fines. Adults often wander some distance from their breeding site and enter stacked hay so it can be hard to find the source of the infestation. Sanitation is the key to dealing with darkling beetles but it can be difficult to find and eliminate all breeding sites of these insects. Fortunately, their development is relatively slow so it takes time for large numbers to develop. Brooms and shop vacs need to be used to clean all accessible fines. Infestations in stored bulk feed are more difficult to address, depending on the amount that is present, how quickly it will be used, and time of year. It may be best to feed out the supply and thoroughly clean the storage area and surroundings before re-filling it. A pyrethrin spray labeled for use in feed storage areas after clean up will help to eliminate surviving insects. Information on blister beetles in alfalfa is available in this factsheet www.ca.uky.edu/entomology/entfacts/ef102.asp

Figure 19. Mealworm -darkling beetle larva.

HOUSEHOLD PESTS Fishing Spider/Nursery Web Spider By Lee Townsend Nursery web and fishing spiders are the largest spiders you are likely to see in Kentucky. They are active hunters that are very similar in appearance and habits to the common wolf spiders that can be seen running across the ground. They move about searching for prey- insects, worms, spiders, and other small creatures. These spiders generally only come inside as accidental invaders but may remain around damp, undisturbed areas of basements, garages, and outbuildings. In spite of their size and rapid movement, they are neither aggressive nor dangerous. However, one could give a painful bite if accidentally mashed or threatened. Reducing hiding places, such as tall grass and clutter, around foundations will discourage these spiders. It is also important to seal as many cracks and crevices as possible to keep them from wandering into structures. Placing sticky cards (Mouse Glue Boards, Roach Motels) along baseboards or undisturbed areas can capture

Figure 17. Darkling/Mealworm beetle.

Figure 18. Blister beetle (left) with distinct "neck", the darkling beetle (right) does not have a narrow neck.

incidental wandering spiders and identify areas that may need control measures.

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Figure 20. Nursery web spider.

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Pest-proofing lawns and play areas By Lee Townsend Summer means the opportunity for lots of outdoor play time but also provides the opportunity for bites and stings along with the normal scrapes and bruises. Spiders, bees, and wasps are among the backyard creatures that are commonly encountered. Some education and regular inspections of potential trouble spots will go a long way toward reducing problems. A proactive approach and a watchful eye is needed with very small children but providing some age-appropriate information on recognizing common pests and learning what to do to avoid problems is part of developing “outdoor readiness”. Here are some examples and countermeasures: • Chiggers and ticks live in areas with tall grass and weeds. Keep grass mowed to remove what chiggers and ticks need: high humidity and protection from excess sunlight. • Spiders tend to remain around undisturbed clutter, indoors and out. It gives them protection and a place for their prey to live. Removing clutter and regularly disturbing what remains will make places undesirable for spiders and their prey. Spiders also can take up residence in tall grass around the supports for swing sets

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and other fixed playthings. These areas should be clipped regularly. Outdoor toy chests, gymsets, and playhouses should be checked weekly – look closely at corners for signs of spiders and webs. The warning coloration – yellow, orange, and black markings on wasps and bees for example - warns of the ability to sting or bite. Usually, these insects are busy collecting supplies for their nests and are completely uninterested in humans. They will only react if disturbed, captured, or crushed. Learning to leave them alone and moving slowly away is a good strategy. Yellowjackets often nest below ground with an opening near surface rocks, landscape logs, or beneath shrubs. Some social wasps and hornets’ nest in hollow spaces in trees, toy chests, and similar places. Seeing them regularly fly to and from a specific spot in the yard suggests a nest. Avoid the area until the presence of a nest can be confirmed and treated. Accidentally approaching a wasp nest can provoke a defensive response. It is better to remain as motionless as possible. Angry bees and wasps go toward movement. Try to remain still and slowly back away from danger rather than run while wildly flailing arms. Sweat bees and other insects often land on the skin. Brushing them off is much better than slapping them, which often results in a sting. Sweet drinks and food can attract bees and wasps, especially later in the summer. Keep food and drink covered when outdoors to minimize attraction. Clean up sweet, sticky spills quickly to avoid attracting many unwanted visitors. Sand boxes, especially when used infrequently, provide the loose, welldrained area that ground-nesting bees and wasps prefer. Thoroughly disturbing the sand every couple of weeks should make the area unsuitable for tunneling insects. Regular inspections and cleaning can detect and remove many potential pest problems. A broom and sprayer with insecticidal soap is usually enough to

dispense with most problems. However, dealing with established wasps and hornets is best left to professionals. Location

Graphs of insect trap counts for the 2012 season are available on the IPM web site at http://www.uky.edu/Ag/IPM/ipm.htm. View trap counts for Fulton County, Kentucky at http://ces.ca.uky.edu/fulton/InsectTraps

Note: Trade names are used to simplify the information presented in this newsletter. No endorsement by the Cooperative Extension Service is intended, nor is criticism implied of similar products that are not named.